T83-03-51 AVCO LYCOMING: Telegram issued February 4, 1983. Applies to Avco Lycoming ALF502 series model turbofan engines.
Unless already accomplished for all engines having less than 100 hours total operating time, within the next 10 engine operating hours, remove all fourth stage turbine rotors assembly P/N 2-141-170-23 or -27 and replace with a rotor which has satisfactorily met the etch inspection requirements for the blades per Avco Lycoming Service Bulletin ALF502-72-0038.
NOTE: Avco Lycoming will provide replacement fourth stage turbine rotors which have been etch inspected per Service Bulletin ALF502-72-0038.
Airplanes may be ferried in accordance with the provisions of FAR 21.197 to a base where the AD can be accomplished.
Upon request of an operator an equivalent means of compliance with the requirements of this AD may be approved by the Manager, Engine Certification Branch, FAA, New England Region.
This airworthiness directive becomes effectiveupon receipt.